The present invention relates to a method for fabricating a semiconductor device; and, more particularly, to a method for forming a hydrogen diffusion barrier layer in a semiconductor device.
In a semiconductor device, an insulation layer for insulating a bottom structure and a top structure can be classified into an inter-layer insulation layer, an inter-metal insulation layer and a passivation layer.
In an insulation layer formation process, plasma and source gas including hydrogen are typically used. Thus, hydrogen atoms, ions and molecules are diffused into a previously formed bottom structure, particularly into a dielectric thin layer of a capacitor, and this diffusion results in degradation of dielectric material properties. Accordingly, a diffusion barrier layer against hydrogen produced when forming an insulation layer is formed prior to forming the insulation layer.
FIG. 1 is a cross-sectional view showing a conventional method for fabricating a semiconductor device.
As shown, a first inter-layer insulation layer 4 is formed on a substrate 22 providing a first and a second active regions 2A and 2B, a device isolation layer 1 and a gate pattern 3. Then, the first inter-layer insulation layer 4 is selectively removed to form a bit line 5 connected to the second active region 2B formed on one side of the gate pattern 3.
A second inter-layer insulation layer 6 is formed on the first inter-layer insulation layer 4, and an insulation layer 7 for passivation is formed thereon.
Subsequent to the second inter-layer insulation layer 6 formation, an adhesion layer 8 for adhering a lower electrode 9 to the second inter-layer insulation layer 6 is formed on a region where a capacitor will be formed. On top of the adhesion layer 8, the capacitor including the lower electrode 9, a dielectric thin layer 10 and an upper electrode 11 is formed. After forming the capacitor, a first diffusion barrier layer 12 for preventing diffusions of hydrogen produced during a subsequent insulation layer formation process is formed in such a manner that it encompasses the capacitor.
Next, a third inter-layer insulation layer 13 is formed, and a contact hole exposing the upper electrode 11 and another contact hole exposing the first active region 2A formed on the other side of the gate pattern 3 are formed thereafter.
Afterwards, a ferroelectric passivation layer 14 for protecting the upper electrode 11 of the capacitor and a barrier metal layer 15 are formed. A first metal line 16 connecting the upper electrode 11 to the first active region 2A is formed thereon. A second diffusion barrier layer 17 for preventing diffusions of hydrogen is formed on an entire surface of the substrate 22 so as to encompass the previously formed structure.
A third diffusion barrier layer 18 is formed on the second diffusion barrier layer 17, and a second metal line 19 is formed thereon. On top of the second metal line 19, a forth diffusion barrier layer 20 and a passivation layer 21 are sequentially formed.
The above first to third diffusion barrier layers 12, 17 and 20 are the diffusion barrier layer against hydrogen and usually use Al2O3 or TiO2 insulation layer. However, this type of insulation layer cannot completely prevent the hydrogen diffusion.
Also, hydrogen in an atom, molecule or plasma state used during the insulation formation process shocks the bottom structure, and this shock effect becomes a critical factor affecting a functional decrease of a semiconductor device.
It is, therefore, an object of the present invention to provide a hydrogen diffusion barrier layer capable of preventing a bottom structure from damage occurring due to hydrogen produced during a semiconductor device fabrication process.
In accordance with an aspect of the present invention, there is provided a method for fabricating a semiconductor device including the steps of: forming a hafnium vanadium oxide (HfVOx) layer on a substrate providing a predetermined structure, the HfVOx layer being used as a hydrogen diffusion barrier layer; and forming an insulation layer on the HfVOx layer.